My invention relates to installation tools and, more particularly, to an installation tool having a barrel assembly which is used to install fasteners and stress plates into insulation on a metal roof deck.
In my copending United States patent application Ser. No. 124,233, filed Feb. 25, 1980, entitled "Fastener Plate and Assembly", I disclose a plastic stress plate and a fastener for use in securing insulation to metal decking. The plastic stress plate includes a hub through which the fastener can be driven. After the fastener passes through the hub and the insulation, it tends to dwell on the metal deck top until penetration takes place. During this period the threads within the hub can strip as a fastener turns seeking to drill and tap the metal deck top. The stripped condition of the plate riding on the smooth or threaded portion of the screw shank affords little resistance for movement between the two components. Therefore, the headed portion of the threaded fastener can more easily pop away from the stress plate or the recess in the stress plate. This can create possible damage to the upper ply of material applied over the insulation. If someone walks on the roof or rolls a rubber wheeled cart on the roof, which is often necessary on industrial buildings, the fastener tends to pop up from the roof. Normally, the uppermost thread terminates that movement, but if too long of an unthreaded portion exists, damage can be done to the roof.
This stripping of the threads in the hub of the plastic stress plate can be avoided by providing an unthreaded portion on the screw which is free to idle in the hub as drilling and tapping take place on the deck top. The unthreaded portion must be outside the barrel so as to be accessible. Further, the plastic plate should rest on the first thread so the fastener and plate cannot move relative to each other. As the demand for thicker and thicker insulation increases, increased screw lengths must be provided and it is difficult to provide a screw having an unthreaded portion properly positioned within the hub as the fastener dwells on the deck top. For all of these reasons, it has been difficult to get building erectors to use screws in such an application even though screws are a logical choice.
Another problem associated with longer screws and thicker insulation is the difficulties encountered in driving such a fastener. In my copending application now U.S. Pat. No. 4,295,394, issued Oct. 20, 1981, I disclose an installation tool barrel assembly capable of handling such long fasteners. However, that installation tool does not of itself prevent the problems associated with the popping up of fasteners.